fix(iso): remove --no-sandbox from chromium (runs as bee user, not root)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

iso/overlay/usr/local/bin/bee-openbox-session

@@ -14,7 +14,6 @@ done
 
 tint2 &
 chromium \
-    --no-sandbox \
     --disable-infobars \
     --disable-translate \
     --no-first-run \